We thank the reviewers for their extensive comments. Where is the novelty (R2+R4) / What is the point of the new proofs (R2)? However, our primary result is to show why it works. Newton's method with a more stable trust-region based method gave rise to a more stable fixed-point (line 131), and Given this, partial derivatives and full derivatives coincide. 'Wiberg optimisation is alternation (see [4]), and an inappropriate description for our work' (R6).

The Spectrum faithfully recreates the 80s original with its rubber keys and classic games, delighting older gamers, while younger players may face a steep learning curve due to tricky controls and tough gameplay. However, modern features like save and rewind help mitigate that frustration. It was made with as few components as possible and connected easily to the TV. Programs ran from compact cassettes, some of you may remember listening to music from these before the advent of CDs. It was possible to program in Basic and play some games. The ZX Spectrum's competitor was the Commodore 64, a popular machine that Retro Games had already recreated.

Every day, we are introduced to new intranet platforms, and along with the brand new features and solutions. Opportunities to upgrade abound – but how much business sense does it even make? How can companies make well-informed decisions about if/when to upgrade after a release has been announced? Given the competitive business benefits an intranet offers, the logical solution does seem to be upgrading as often as possible. However, upgrading does come with a hefty price tag and more importantly, quite a lot of disruption. The answer for organizations lies in striking an efficient balance in order to truly leverage the benefits of an upgrade.